Custer, T. W., and Pitelka, F. A., 1977, Demographic features of a lapland
longspur population near Barrow Alaska: The Auk, v. 94, no. 3, p. 505-525.

Abstract:

Breeding density, clutch size, hatching and fledging success, and survival of
adult Lapland longspurs (Calcarius lapponicus) were monitored over a 7 yr
period near the Naval Arctic Research Laboratory, Barrow, Alaska [USA].
Nesting begins as soon as the tundra starts to clear of snow and appears to be
timed so that the young of the year reach independence before the end of
adult insect emergence. Arthropod prey become abruptly scarce after the
period of insect emergence and thus probability of success for late broods is
low. Time of nesting is also discussed in relation to factors of predation and
timing of molt. At least 42.9% of males and 45.4% of females survived the
next season after 1 yr of age. Maximum longevity observed for both sexes
was 6 yr. Mean clutch size for all years investigated was 5.06 eggs per
clutch. Clutch size showed both yearly and seasonal variation. The data
indicate that timing of nesting is the chief factor in the observed clutch size
differences, further modified by habitat quality, second nesting attempts and
probably age of female. Over a 4 yr period the longspur breeding population
on a 17 ha study plot declined from 15 to 2 breeding females. Life-table
analysis indicates that low fledgling success for 3 consecutive years
apparently was the main cause of this decline. Overall mean egg success was
44.0%, but close to 60% in 4 yr is considered more normal. The low egg
success was due to 3 consecutive years of high predation, which may have
been related to the disrupted lemming cycle of the Barrow region.

Keywords:

USA, Calcarius-lapponicus, insects, arthropods, lemming, cycle, adult, male,
female, longevity, breeding, density, clutch size, molting, egg, mortality